How the Guides on This Site Are Written

We sell introductions to machine shops. That is a reason to be suspicious of our technical advice, so here is exactly how it is produced.

Who writes them

Ryan runs the matching side of this site. He reads every RFQ that comes in, decides which shops it goes to and writes the guides here. There is no content agency and no rotating cast of freelancers behind these guides. One person writes them, which means one person is accountable for them.

Where the numbers come from

Every figure on this site traces to one of four kinds of source, and nothing else.

• Published material standards. ASTM B348, B265, B338 and F136, AMS 4928 and 4911, ISO 5832, EN 10204 for certification. Specification minimums are quoted as minimums, not as what your heat will test at.
• Tool supplier application data. Cutting speeds and feeds come from the published titanium guidance of the major carbide makers, quoted as starting ranges because that is what they are.
• Standard reference handbooks for physical properties such as density, modulus and thermal conductivity.
• What shops tell us when we ask them. Where a statement rests on that rather than a document, the text says so with words like "shops typically" instead of stating it as fact.

Why everything says "typical"

Because it is. A tolerance table on a sourcing site is a starting point for a conversation, not a commitment anyone has made to you.

The shop that quotes your part is the only party that can say what it will hold on your geometry, in your grade, with its machines and its fixture. So our tables are labelled typical and our ranges are ranges. If you ever see a number on this site presented as a guarantee, it is a mistake and we would like to hear about it.

What we refuse to publish

• Invented proof. No client counts, no years in business, no network size, no testimonials, no logo walls, no case studies about parts that do not exist.
• Certifications we do not hold. We are not ISO 9001, AS9100, ISO 13485 or NADCAP accredited. Those are questions we ask shops on your behalf, not badges we wear.
• Paid placement. No shop can pay to be named, ranked or recommended in an article. There is no premium tier and no sponsored post.
• Affiliate links. There are none on this site. When we point at an outside resource it is because it is the best one we know, and it earns us nothing.
• Competitor attacks. We will describe how a marketplace model differs from ours, factually. We will not run down a named company to sell an introduction.
• Filler. No guide exists to hold a keyword. If we have nothing useful to say about a topic, the page does not get written.

Reviews and dates

Every guide carries a publication date, and an updated date once it has been revised. Material standards change, tooling improves and stock availability moves, so a guide that has not been looked at in two years should be treated as a guide that has not been looked at in two years. The date is there so you can make that judgement yourself.

Where a guide has been substantially rewritten rather than lightly edited, the updated date moves and the change is noted at the point it happened.

Corrections

If something here is wrong, tell us and it gets fixed. Email with the page and what is wrong with it.

We will reply within 24 business hours. A factual error gets corrected on the page, and if the error was material, the correction is noted rather than quietly swept away. We would rather carry a visible correction than a silent inaccuracy, because a sourcing site that cannot be trusted on a tolerance table cannot be trusted on a supplier either.

Conflicts of interest, stated plainly

We are paid by machine shops, for matched requests. That is our only revenue.

It creates one obvious bias: we benefit when you send an RFQ. So read the advice with that in mind, and notice what it actually says. Several guides here tell you that a stainless or aluminium part would be cheaper, that Grade 2 would do the job you specified Grade 5 for, that a certificate you asked for is probably unnecessary, and that a tight block tolerance is costing you money for nothing. Each of those makes your order smaller. We publish them anyway, because a buyer who gets honest advice comes back with the next part.